Device and Method for Stabilizing a Chair on Unstable Surfaces

ABSTRACT

The present invention is a device and method for stabilizing a chair on unstable ground. The device is particularly suited for chairs having horizontal or longitudinal leg support sections that contact the ground. The device comprises an elongated platform body having a longitudinal axis along its length and a horizontal axis along its width. The platform body has an upper surface, a ground contacting surface and a perimeter edge. The upper surface comprises at least one adapter positioned along the longitudinal axis for affixing the device to the horizontal or longitudinal leg support section of a chair. The increased surface area provided by the device reduces or eliminates instability when the chair is used on unstable surfaces such as sand, snow, gravel or grass.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a device that can be affixed to the horizontal or longitudinal leg supports of a chair to reduce or prevent the chair from shifting or sinking on unstable ground. More specifically, the device distributes the weight of the user over a larger surface area reducing or preventing the chair legs from sink in sand, gravel, snow or grass.

2. Prior Art

Folding chairs are easily transported because of their compact size and are a popular device for use with outside activities such as camping, sun bathing and picnics. There are several different types of folding chairs that are frequently used including the beach folding chair, which is generally lower to the ground than a regular sized folding chair, the standard height folding chair and the lounge chair or chaise lounge. Their popularity is derived from a compact and lightweight construction and relatively low cost.

The material and structural configurations of folding chairs have been designed to keep the cost of construction and assembly to a minimum. In this regard, the leg supports are often made of a single piece of structural material configured with horizontal portions connecting sets of legs. These horizontal portions may be provided parallel to the width of the chair or parallel to the length as in some lounge chairs. This type of construction reduces the number of parts needed to assemble the chair and thereby reduce the cost of production. In addition, the weight bearing structural elements of a chair are generally made of a lightweight tubular stock that is easy to cut and bend into the desired shape. This tubular stock has a general external diameter from one-half inch to about one and a half inches and is of sufficient gauge to provide structural integrity.

When used on a solid flat surface such as cement or asphalt these folding chairs are relatively stable during use. However, when placed on an unstable surface such as sand or snow they have a tendency to sink. To a lesser degree the stability of the chair is also affected when placed on surfaces such as gravel and grass. The extent to which the chair becomes less stable is often dependent upon the weight of the user. Increasing weight generally increases the instability of these chairs on unstable surfaces.

The effect of sinking in sand or snow and the side to side instability that can occur on grass or gravel applies forces at angles the structure was not intended or designed to support. Depending on the amount of weight applied under these conditions there can be a catastrophic failure of the structural integrity resulting in the chair collapsing and potential injury to the user.

U.S. Pat. No. 4,915,335 discloses a chair comprising stabilizing adapters secured to the curved transitions of and extend beyond the chair's legs. These adapters prevent lateral tipping or rolling of the chair to one side or the other. While these adapters help to stabilize the folding chair from side to side motion they do not provide sufficient surface area to reduce or prevent sinking of the legs on unstable surfaces such as sand.

Consequently, there is a need in the field for a device that can stabilize these types of chairs on a variety of surfaces and reduce or prevent potential injury to potential users.

SUMMARY OF THE INVENTION

The present invention is an adapter for stabilizing a chair on unstable ground. Particularly for chairs that have horizontal or longitudinal leg support sections contacting the ground. The device comprises an elongated platform body having an upper surface, a ground contacting surface, a perimeter edge and at least one adapter positioned along its longitudinal axis on its upper surface. The adapter allows the device to be affixed to the horizontal or longitudinal leg support section of the chair. The increased surface area provided by the device reduces or eliminates instability when the chair is used on unstable surfaces such as sand, snow, gravel or grass.

In one embodiment, the chair is a folding chair, such as a beach chair or lawn chair, or a folding lounge chair, such as a chaise lounge.

In another embodiment, the adapter is a groove able to receive the horizontal or longitudinal leg support section of a chair. The device may be affixed to the leg support section by adhesive, screws or straps, such as Velcro™ or zip-tie. If screws affix the device, one or more apertures may be provided within the base of the adapter or groove. If straps affix the device, a pair of elongated apertures may be provided one on either side of the adapter or groove. The adapter may also be provided as a clip that allows the device to rotate about leg support section once affixed to the chair. In each of these configurations, the device may further comprise one or more structural supports extending perpendicular to the longitudinal axis and from either side of the adapter or along the ground contacting surface of the elongated platform body.

In another embodiment the device is adjustable. In this configuration, the device is provided in two sections with each section having an adapter for receiving the leg support section of a chair. The first section comprises slide grooves along each length of the perimeter edge facing the longitudinal axis. The other section comprises a slot along the longitudinal axis able to receive the adapter on the first section and a perimeter edge able to be received by the slide grooves of the first section.

Another aspect of the present invention is a method for stabilizing a chair having horizontal or longitudinal leg support sections on unstable ground. The method comprises affixing a device to the horizontal leg support section of the chair. The increased surface area provided by the device reduces or eliminates instability when the chair is used on unstable surfaces such as sand, snow, gravel or grass.

Other aspects and embodiments of the inventions are found throughout the specification.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of the invention mounted on a horizontal leg support section of a chair.

FIG. 2 shows profile views of the invention A) side view, B) bottom view, C) top view and D) end view.

FIG. 3 shows an end view of the A) snap clip cap configuration, B) hinged snap clip configuration and C) groove with zip tie.

FIG. 4 shows a lounge chair comprising the device attached to the chair's horizontal leg supports.

FIG. 5 shows a lounge chair comprising the device attached to the chair's longitudinal leg supports.

FIG. 6 is a perspective view of the invention in an adjustable configuration.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

Unless defined otherwise, all terms used herein have the same meaning as are commonly understood by one of skill in the art to which this invention belongs. All patents, patent applications and publications referred to throughout the disclosure herein are incorporated by reference in their entirety. In the event that there is a plurality of definitions for a term herein, those in this section prevail.

The term “chair” as used herein refers to any device that may be used for resting. This includes, for example, a chair wherein the user sits relatively upright or reclined, a chaise lounge or lounge chair wherein the user can lay or sit up with legs relatively extended or a platform on which an individual can sit, recline or lay. A platform can include a table or table-like structure that may be used for resting. In each case, it is preferable that the chair has horizontal or longitudinal leg support sections that contact the ground during use.

The term “affixing” as used herein refers to any method know to those skilled in the art for connecting one element of the invention to another. For example, affixing the device to the leg support section of a chair may be accomplished by an adhesive, one or more screws, one or more bolts, one or more rivets, Velcro™, one or more zip-ties (FIG. 3C), one or more straps or one or more snaps.

The term “unstable” as used herein, in reference to the ground or a surface on which the chair is placed, refers to a surface that when a force is applied does not retain its original shape. For example, when a folding chair having horizontal leg support sections is placed on sand and weight is applied, the horizontal leg supports will sink into the sand. The depth to which the leg supports will sink and the magnitude of the resulting forces on the structural integrity of the chair will depend on the weight applied. Consequently, sand under these conditions would be considered an unstable surface. This can occur on other surfaces as well such as grass, gravel and snow.

The term “platform” or “elongated platform” as used herein, refers to the relationship of the length, width and thickness of the body of the device. Generally the platform body has a width and length that may or may not be the same but whose thickness is substantially less than either its length or width. For example, an elongated platform describes the body as having a width less than its length and a thickness substantially less than either its width or length. The length and width of the body are designed to provide a significantly larger surface area then that provided by the leg supports of the chair alone. The thickness of the body is sufficient to maintain the platform's rigidity when a variety of different weights are applied to the chair.

The term “adapter” as used herein, in reference to the element of the invention that is used to affix the device to the horizontal leg support section of a chair, is any device known to those skilled in the art for this purpose. For example, the adapter may be a semicircular groove positioned along the longitudinal axis on the upper surface of the platform body. This groove may be provided with an internal diameter slightly smaller than the exterior diameter of the leg support section of a chair and having an arc greater than 190 degrees. A groove having an arc of this degree can provide sufficient clamping ability to allow the adapter to stay tightly affixed to the leg support section during use.

The term “aperture”, “cylindrical adapter” or “slit aperture” as used herein refers to openings in the platform body and/or the adapter that allow fasteners such as a screw, a rivet, a strap, Velcro™ or a zip-tie to be used in affixing the device to the leg support section of a chair. For example, a cylindrical aperture, driven through the platform body within the adapter, may be used to receive and guide a screw into the leg support section to anchor the device. Alternatively, slit apertures 30 may be provided through the platform body and on either side of the adapter. A strap, Velcro™ strip or zip-tie can be inserted through the first slit aperture 30 around the leg support section positioned in the adapter, then through the second slit aperture 30 and fastened together thereby securing the device in place (FIG. 3C).

The present invention, as shown in FIGS. 1-3, is a device and method for using the device 10 for stabilizing a chair on unstable ground. It is particularly suited for chairs that have horizontal leg support sections in contact with the ground. The device comprises a platform body 12 having an upper surface 14, a ground contacting surface 16, a perimeter edge 18 and at least one adapter 20 positioned along its horizontal axis on its upper surface 14. The adapter 20 allows the device to be affixed to the horizontal leg support section of the chair. The increased surface area provided by the device reduces or eliminates instability when the chair is used on unstable surfaces such as sand, snow, gravel or grass.

The platform body 12 of the device is designed to provide a larger surface area for the distribution of weight than that provided by the existing chair's legs. The dimensions of the platform will vary depending on its location on the chair leg, whether it is connected in a fixed or rotatable configuration and the type of surface on which the chair will be used. Consequently, the length and width may be the same forming a square platform or different creating a rectangular platform. If the length is substantially longer than the width, the platform may be considered to have an elongated rectangular shape.

The thickness of the body may also vary depending on the platform's dimensions, the amount of weight that the chair is intended to support the type of material used to construct the platform and the type of surface on which the chair will be used. In this regard, the platform may be made of a variety of materials and selection of the appropriate material for use under specific conditions is within the knowledge of those skilled in the art. For example, the platform may be made of a metal, polymer, carbon fiber, fiberglass, ceramic or other composite of natural or synthetic materials. If the material selected is rigid such as a metal or ceramic the thickness desired could be determined based on the amount of weight for which the chair is designed to support. That thickness will be such that the metal platform does not bend or the ceramic platform fracture. If the material is semi-rigid such as a polymer, fiberglass or carbon fiber, the thickness desired will be that which does not result in significant flexing of the material under the proscribed weight the chair can support. Significant flexing, which reduces the stabilizing effect of the device, can also be minimized by providing structural supports 22 within the platform that increase rigidity and reduce flexing.

Structural supports 22 may be provided on the upper surface (FIG. 3B), the ground-contacting surface (FIG. 3A) or both and they may be provided along the longitudinal axis, horizontal axis or both. The addition of structural supports 22 to increase rigidity in a desired direction may be provided in a parallel or random configuration. If structural supports 22 are desired along both axes, they may be provided in an even or random crosshatch design. The placement, thickness and/or height will vary depending on the amount of support needed and the material from which the platform is constructed. This can be easily determined by one skilled in the art or though actual weight testing of the device in use.

In one embodiment, the structural supports 22 are provided parallel to the horizontal axis at specific locations along the longitudinal axis on the upper surface 14 of the platform (FIG. 2). These supports may also form the adapter 20 or a portion of the adapter 20 that cradles the horizontal leg support section of the chair. For example, the structural support may be provided at a thickness and height from which a semi-circular groove 26 can be formed or cut along the longitudinal axis for receiving the chair's horizontal leg support. Alternatively, these structural supports 22 may extend from the adapters 20 to the edges of the platform wherein they not only increase the structural integrity of the platform, but also act as structural side supports for the adapters 20.

In another embodiment, the platform body 12 may be slightly curved such that the ground-contacting surface is slightly concave. In this configuration, the flexibility of the material is used to remove the curvature when weight is added to the chair, flattening the platform into its most effective configuration. Alternatively, structural supports 22 may be incorporated on the ground-contacting surface 16 and parallel to the horizontal axis to maintain this curvature.

In some instances, the method of preparing the platform determines the type of material used for its construction. For example, if reducing costs is desired, extrusion or form molding methods may be used to construct the platform. In this regard, a polymer or aluminum may be the material of choice for an extrusion method or sheet metal for a form molding method. In each case, long linear sections of the platform can be produced that may be later cut into desired lengths.

Other shapes and configurations that provide an esthetic appearance may also be utilized. More specifically, the platform may be provided in a shape that is not square or rectangular. The platform may be designed in a freeform or other shape that appeals to the user and provides the increased surface area for stabilizing the chair. For example, if the chair is being used on grass the platform could be colored green and have a freeform appearance of grass. Alternatively, the platform could have an architectural appearance transforming the tubular horizontal leg support section into an aesthetically pleasing rectangular pedestal base.

In another embodiment the platform body 12 may be adjustable (FIG. 6). A variety of configurations may be utilized to provide an adjustable platform body. For example, the platform body may be provided in two sections. The first section may have slide grooves 36 along its longitudinal perimeter edges and the second section having its longitudinal perimeter edges able to be received by the slide grooves 36 of the first section. Further, each section comprises one or more adapters 20 on its upper surface 14. One of the sections is provided with a slot 38 running longitudinally about the center of the platform body 12 and about one-third to one-half its length. The slot 32 is slightly larger than the width of an adapter 20 so that when the two sections are connected, the length may be adjusted with the adapter 20 fitting easily within the slot 38.

The adapter 20 is positioned on the upper surface 14 of the platform and is provided to cradle and/or affix the device to the horizontal leg support section of a chair. A variety of configurations may be envisioned and the examples discussed below are provided merely as illustrations and not by way of limitation. When designed to cradle the horizontal leg support, the adapter 20 is a groove 26 positioned along the longitudinal axis of the platform. The groove 26 may be formed in the upper surface 14 of the platform, cut into structural supports 22 provided parallel to the horizontal axis along the upper surface 14 of the platform or a raised ridge containing a groove 26 for receiving the horizontal leg support. To accommodate a variety of horizontal leg supports, the groove 26 may have a V-shaped profile. This would allow for narrower diameter leg supports to fit near the base of the groove 26 while larger diameter leg supports will be bracketed near the top of the groove 26. Alternatively, a semi-circular groove 26 may be slightly smaller than the diameter of the leg support so that it fits snuggly on the leg support.

A variety of methods are known to those skilled in the art for securing the device to a horizontal leg support section of a chair. In its simplest form the groove 26 comprises apertures 28 for receiving a screw or rivet that may be driven through the horizontal leg support affixing the device to the chair (FIG. 2-3). Alternatively, the groove 26 may comprise an adhesive having a protective cover. When the cover is removed the horizontal leg support may be pressed into the groove 26 adhering the device to the horizontal leg support. Another method includes adhering one portion of a Velcro™ strip within the groove 26 and securing the other portion to the horizontal leg support. In each of these methods the orientation of the device is fixed.

Other methods that allow the device to rotate in place after being affixed to the horizontal leg support include providing the adapter 20 in the form of a snap clip 24, a hinged snap clip 34 (FIG. 3B), a C-clamp or a snap cap 32 (FIG. 3A). In a snap clip 24 configuration, the adapter is a semi-cylindrical groove 26 in which the internal diameter is slightly smaller than the external diameter of the horizontal leg support. In addition, the semi-cylindrical groove 26 envelops 60 to 75% of the exterior of the horizontal leg support, snapping tightly onto the leg support while allowing the device to be rotated as desired.

In a hinged snap clip configuration, the adapter 20 is a semi-cylindrical groove 26 having a clip along the top edge of one side and a hinged cover 34 on the other side. The hinged cover 34 has a corresponding snap along its unhinged edge to engage the clip on the groove 26. The horizontal leg support is fitted within the groove 26 and the cover is rotated over the exposed portion of the leg support and snapped in place. The snap provided on the lip of the cover engages the corresponding clip on the other side of the groove 26 securely and rotatably affixing the device to the horizontal leg support section. Further, in this configuration, the groove 26 may envelope 30 to 75% of the leg support before the cover is clipped or snapped in position.

When the adapter 20 is a C-clamp, the platform may or may not comprise a groove 26 to assist in aligning the horizontal leg support section before securing the clamp in place. In this configuration the C-clamp may be provided as a separate piece that is secured to the platform by adhesive, Velcro™. Alternatively, the platform may be provided with apertures that allow the C-clamp to be screwed or riveted in place. In another configuration one side of the C-clamp may be hingeably affixed to the upper surface 14 and positioned along the longitudinal axis of the platform. The free end of the C-clamp is provided with a clip or snap or other connecting means that allows the C-clamp to be closed securely thereby affixing the device rotatably to the horizontal leg support.

In a snap cap configuration, the adapter 20 is a groove 26 that is provided with clips on both sides of the groove 26. A separate cap cover 32 is provided with corresponding snaps along its sides. When the horizontal leg support is positioned in the groove 26 the cap 32 cover is positioned over the groove 26 and snapped in place. This affixes the device to the horizontal leg support section such that it may be rotated into a desired position. Further, in this configuration, the groove 26 may envelope 30 to 75% of the leg support before the cap 32 is snapped in position.

While these are a few types of adapters 20 that may be utilized with the present invention, they are by no means the only adapters 20 that will effectively affix the device to the horizontal leg support sections of a chair. Correspondingly, those skilled in the art may utilized other existing methods similar to those described for securing the device. Consequently, the present invention is not intended to be limited to only those adapters 20 described.

In use the device is provided in groupings of two or more and in variable sizes to fit the length of a variety of horizontal leg supports. Proper selection of the device in longer lengths will depend on the length of the horizontal leg support section on which the device is to be affixed. The device may be prepared using an extrusion method and cut into standard sized lengths such as 12″, 18″, 20″, 24″, 30″, 36″ and 48″. The user may decide whether to apply a length that stretches across the entire length of the horizontal leg support or only a portion. When the desired length is determined and obtained, the device is extracted from its packaging. The horizontal leg support sections of a chair are aligned with the adapter 20 provided on the upper surface 14 of the platform body 12. Pressure is then applied until the horizontal leg support snaps into the adapter 20 securing the device to the leg support (FIG. 1). When the chair is in the folded position the device may be rotated so that the platform body 12 is parallel to the seat and backrest. In the open position the device is rotated so that the ground contacting surface 16 is parallel to the surface on which the chair will be used. This procedure may also be utilized for lounge chairs that have horizontal leg support sections similar to a folding chair (FIGS. 4 and 5). For lounge chairs that are injection molded and do not fold or only a portion folds, the device may be rotatably affixed so that when these lounge chairs are stacked one inside the other the device may be rotated so that it does not interfere with stacking.

For chairs that do not fold or for which rotation of the device parallel to the seat and backrest is not required or desired, the device may be secured in a fixed position on the horizontal leg support sections with one or more screws or rivets. In this configuration the device is positioned on the horizontal leg support in the desired orientation. Then screws or rivets are driven through the apertures 28 provide in the platform body 12 along the longitudinal axis and into the horizontal leg supports securing the device in place. Alternative, apertures may be drilled into the horizontal leg supports that align with the apertures 28 provided along the longitudinal axis of the platform body 12. Screws may be inserted from the ground-contacting surface of the platform body 12 through the apertures 28 in the horizontal leg supports. The device may then be secured in place with nuts.

While all of the fundamental characteristics and features of the device and method for stabilizing a chair on unstable ground have been described, it should be understood that various substitutions, modifications, and variations may be made by those skilled in the art without departing from the spirit or scope of the invention. Consequently, all such modifications and variations are included within the scope of the invention as defined by the following claims. 

What is claimed is:
 1. A device for stabilizing a chair on unstable ground, wherein said chair has horizontal or longitudinal leg support sections that contact said unstable ground, said device comprising: an elongated platform body having a longitudinal axis along its length and a horizontal axis along its width said platform body having an upper surface, a ground contacting surface and a perimeter edge, said upper surface comprising at least one adapter positioned along said longitudinal axis for affixing to said horizontal or longitudinal leg support section when said longitudinal axis is parallel to said horizontal or longitudinal leg support section.
 2. The device according to claim 1, further comprising at least one structural support extending parallel to said horizontal axis and from either side of said at least one adapter.
 3. The device according to claim 1, wherein said at least one adapter is at least one snap clip adapter that fastens onto said horizontal or longitudinal leg support section.
 4. The device according to claim 1, wherein said at least one adapter is a groove able to receive said horizontal or longitudinal leg support section, said groove further comprising at least one aperture extending through said elongated platform body for affixing said device to said horizontal or longitudinal leg support section.
 5. The device according to claim 1, wherein said platform body further comprises a plurality of structural supports positioned along and parallel to said horizontal axis on said upper surface, on said ground contacting surface or on both said upper surface and said ground contacting surface.
 6. The device according to claim 1, wherein said chair is a folding chair or folding lounge chair.
 7. The device according to claim 1, wherein said chair is a lawn chair, a beach chair, a lounge chair or a chaise lounge chair.
 8. The device according to claim 1, wherein said unstable surface is grass, gravel, snow or sand.
 9. The device according to claim 1, wherein said at least one adapter is at least one snap clip adapter or a groove.
 10. The device according to claim 9, wherein said groove further comprises at least one aperture extending through said platform body.
 11. The device according to claim 10, wherein said at least one aperture is at least one cylindrical aperture.
 12. The device according to claim 10, wherein said at least one aperture is at least one pair of slit apertures positioned about either side of said longitudinal axis.
 13. A device for reducing or preventing a tubular horizontal or longitudinal leg support section of a chair or a lounge chair from sinking when used on sand, said device comprising: an elongated rectangular platform body having a longitudinal axis about its length and a horizontal axis along its width, an upper surface, a sand contacting surface and a perimeter edge, said upper surface comprising at least one snap clip adapter positioned along said longitudinal axis for securely receiving a horizontal or longitudinal tubular leg support section of said chair or lounge chair when said longitudinal axis is parallel to said horizontal or longitudinal tubular leg support section, wherein said sand contacting surface provides a surface area that reduces or prevents said horizontal or longitudinal tubular leg support section from sinking when used on sand.
 14. A device according to claim 13, further comprising at least one aperture extending through said elongated platform body for affixing said device on said horizontal or longitudinal tubular leg support section.
 15. A method for stabilizing a chair on an unstable surface, comprising the steps of: affixing a device on a horizontal or longitudinal leg support section of said chair, wherein said device comprises an elongated rectangular platform body having a longitudinal axis about its length and a horizontal axis along its width, an upper surface, a ground-contacting surface and a perimeter edge, said upper surface comprising at least one adapter positioned along said longitudinal axis for securely receiving said horizontal or longitudinal leg support section of said chair when said longitudinal axis is parallel to said horizontal or longitudinal leg support section; and placing said chair with said device on said unstable surface wherein said device provides a surface area that stabilizes said chair.
 16. A device for stabilizing a chair having horizontal or longitudinal leg support sections on unstable ground, said device comprising: a first and a second elongated platform bodies each having a longitudinal axis along their length and a horizontal axis along their width, said first platform body having an first upper surface, a first ground contacting surface and a first perimeter edge, said first upper surface comprising at least one adapter positioned along said longitudinal axis for affixing to said horizontal or longitudinal leg support section when said longitudinal axis is parallel to said horizontal or longitudinal leg support section, said first upper surface having two slide grooves one along each length of said perimeter edge and facing said longitudinal axis, said second platform body having a second upper surface, a second ground contacting surface, a second perimeter edge and a slot, said second upper surface comprising at least one adapter positioned along said longitudinal axis for affixing to said horizontal or longitudinal leg support section when said longitudinal axis is parallel to said horizontal or longitudinal leg support section, said second perimeter edge able to be received by said slide grooves of said first platform body and said slot positioned about the center and parallel to said longitudinal axis able to receive said at least one adapter of said first upper surface.
 17. The device according to claim 16, wherein said at least one adapter is a groove able to receive said horizontal or longitudinal leg support section, said groove further comprising at least one aperture through said elongated platform body for affixing said device to said horizontal or longitudinal leg support section.
 18. The device according to claim 16, wherein said chair is a folding chair, a folding lounge chair, a lawn chair, a beach chair, a lounge chair or a chaise lounge chair.
 19. The device according to claim 16, wherein said unstable surface is grass, gravel, snow or sand.
 20. The device according to claim 16, wherein said at least one adapter is at least one snap clip adapter. 